For insights into this _particular_ example -- you might chase work by John
Ostrom (JH Ostrom). While I can't remember the exact references, I clearly
remember several lengthy review articles discussing his theories of the
development of feathers/wings/flight in small bipedal reptiles -- where
wings were (in their more terrestrial phase) insect-batting-down devices. His
illustrations look remarkably like the Northern Mockingbird.
Kate McCain "Bibliometrics R Us"
College of Information Studies
Philadelphia, PA 19104
mccainkw at duvm.ocs.drexel.edu